(1) Field of the Invention
The invention relates to a system and an accompanying method for testing light-emitting devices, and more particularly to the test station/equipment and the test method that utilize solar cells/cell modules.
(2) Description of the Prior Art
In the art, to obtain the total luminous flux (or say, lumen) of a light-emitting device, an integrating sphere is usually used. The operation of a typical integrating sphere can be concisely elucidated in FIG. 1. As shown, an integrating sphere 11 is connected with an optical spectrum analyzer 14 via an optical fiber 12. The integrating sphere 11 further includes thereinside a diffusing baffle 13. An LED to be tested 15 is positioned at an input port 16 located at a lower part of the integrating sphere 11 in FIG. 1. An output port 17 for transporting out the diffused light originally emitted by the LED 15 is included in an upper part of the integrating sphere 11 as shown.
In the testing, while the LED 15 is energized, a light is received by the integrating sphere 1 through the input port 16. In the integrating sphere 11, the light experiences various reflection and diffusion, and the diffused light finally reaches the output port 17 to be further transported to the optical spectrum analyzer 14 via the optical fiber 12. After a comparison with data from testing a reference known light under the same testing setup, the total luminous flux of the LED 15 can be obtained. However, the aforesaid testing mode constructed with the integrating sphere 11 is only better applicable to the light sources with specific directivity, not to all kinds of light sources. Further, the size of the integrating sphere 11 and the accompanying facilities usually limits the usage of the integrating sphere 11 only in the laboratory. In addition, reciprocally positioning and replacing the light-emitting devices (LED 15 for example) for testing outside the input port 16 can sometimes imply an inevitable labor load and time-consumption. More, the cost of the integrating sphere 11 is often not affordable to all those they need.
Aiming at the foregoing disadvantages in applying the integrating sphere 11, a total luminous flux testing system 20 as shown in FIG. 2 by a perspective view as well as FIG. 3 by a cross-sectional view is proposed. In this effort, the testing system 20 is introduced to have solar cell modules 21 mounted to each interior wall of a testing box 22 (all six interior walls as shown). The energized device under test (DUT) 23 mounted on a conveyor belt 24 is shipped to go through the testing box 22, entering from an inlet 28 and leaving from an outlet 29 at a lower portion of the testing box 22. While the DUT 23 is in the testing box 22, photo energy of the energized DUT 23 is received by the solar cell modules 21.
In the testing system 20, two pathways are provided to forward the received photo energy of the energized DUT 23 inside the testing box 22: one connecting directly to a processor 25 via a cable 26, and another connecting to an optical spectrum analyzer 27 via an optical fiber 27a and then further to the processor 25. By integrating the data from the two pathways, the processor 25 can then calculate the total luminous flux of the DUT 23.
By compared to the integrating sphere apparatus in FIG. 1, the testing system 20 in FIG. 2 is superior in cost and maintenance. The non-stop transportation of the DUT 23 by the conveyor belt 24 does also provide the advantage in saving testing time. Further, the accuracy in computing the total luminous flux by two difference entries, one direct from the solar cell modules 21 and one from the optical spectrum analyzer 27, can be better guaranteed.
Nevertheless, in either the integrating sphere apparatus of FIG. 1 or the testing system of FIG. 2, only the value of the total luminous flux for the DUT can be obtained. It is all right for the aforesaid apparatus and the system to determine the quality of the DUT if the DUT includes a single light-emitting element. Yet, to a DUT having plural light-emitting elements (for example, the light bar-shape DUT shown in FIGS. 2 and 3), the aforesaid apparatus and the system mean nothing in locating the problem element or elements. Namely, a number of an accurate total luminous flux provides no immediate help to locate a dumb element in the DUT having plural light-emitting elements. Thus, additional quality control effort in the manufacturer end must be spent so as to promptly correct the problem device and so as to ensure the yield of the devices.